CUPERTINO, Calif. — After three years as chief executive of Apple, Timothy D. Cook is starting to crystallize his vision for the company.

Apple on Tuesday introduced a highly anticipated smartwatch, which combines health and fitness monitoring with mobile computer capabilities like maps. The company also introduced two iPhones with larger screens.

The smartwatch, named the Apple Watch, is a miniature computer strapped around the wrist and is the first product made under Mr. Cook’s leadership that branches Apple into a new type of product: a device in the growing field of fitness-tracking computers that can be worn on or around the body.

Although the Apple Watch is the company’s first wearable computer, it enters a crowded field. Samsung, Pebble and Sony lead the pack of companies producing these new devices, and sales are growing quickly. But the devices are nowhere near as popular as smartphones. IDC, the research company, estimates that 19 million smartwatches will ship in 2014, much lower than the 1.2 billion smartphones that it expects will ship this year.

And despite the fanfare with which the news media has greeted Apple’s first wearable device, analysts have expressed mixed views about its potential to become mainstream. Can the smartwatch be a late entrant to a market but eventually dominate as Apple did several times before under its former chief, Steven P. Jobs?

“Jobs made that work with the iPod,” said Carl Howe, an analyst at the Yankee Group. “He certainly made it work with the iPhone. Question is, Are they going to be able to do the same thing with a watch? I wouldn’t bet against them at this point.”

Mr. Cook said in an interview that the new watch indicated that the company was still innovative.

“For us, it’s never been about being first. It’s been about being the best,” he said. “And I think we just launched the Apple watch that is sort of in a category by itself that will redefine what people expect of products in the category.”

Video

Times technology columnist Molly Wood says Apple has a chance to make smart watches a hit.Published OnSept. 9, 2014CreditCreditRebekah Fergusson for The New York Times

The new iPhones are significant upgrades for Apple’s smartphone lineup, still by far the company’s largest source of profit. They cater to a growing appetite among consumers for bigger screens, similar to what happened with televisions.

And they are a rare instance of Apple’s following market trends instead of creating them; Samsung, Apple’s chief rival, has captured a major share of the smartphone market with large phones.

Apple displayed the products in front of a packed auditorium here at the Flint Center for the Performing Arts, the same spot where the company introduced the Macintosh in 1984.

Apple said that to use the Apple Watch, someone must also use one of its more recent iPhones.

The watch will have a strong focus on health. An app called Fitness tracks statistics for different exercises, like bicycling or running, an accelerometer tracks movements and a heart rate sensor helps measure the intensity of workouts.

The watch has a rectangular screen for a face with a flexible display and comes in two sizes. A crown on the side acts as a digital dial, which can be turned to zoom in; tapping the crown returns to the main menu. The watch can be attached to six strap styles, like stainless steel and leather.

The smartwatch can run various apps, like a calendar, map navigation and a music player.

The smartwatch will rely on so-called inductive charging to replenish the battery. Some consider it a form of wireless charging, but technically, it still requires a magnet that attaches to the back of the watch from another device.

The watch will take advantage of Siri, Apple’s tool for controlling the device with voice commands. Pushing on the crown activates Siri, and a command like “What movies are playing nearby?” will prompt the watch to load show times for nearby theaters.

Apple also said it would release a tool kit for software developers to build apps for the watch. It said many companies had already made such apps, including W hotels, Pinterest and BMW.

Image

The iPhone 6 and the 6 Plus, right.CreditJim Wilson/The New York Times

James McQuivey, a consumer technology analyst at Forrester Research, said the Apple Watch had already accomplished one thing, even though the device will not be in stores until 2015.

“It has firmly established the smartwatch as a category, one with unique properties requiring a unique solution, as opposed to a miniature smartphone pushed down onto your wrist,” he said.

Apple said that there would be three versions of the watch — Apple Watch, Apple Watch Sport and Apple Watch Edition — and that pricing would start at $350.

Employees working on the project, who spoke on the condition of anonymity, have said that Apple wanted to introduce the product last year, but had to wait until this year to finish developing the hardware and software and to give developers time to make apps for the device.

Mr. Cook said Apple took its time to figure out how to devise a software interface that made sense on a small screen, among other challenges.

“You don’t want a phone strapped to your wrist. That’s not what the consumer wants,” he said.

The two new iPhones, the iPhone 6 and the iPhone 6 Plus, measure 4.7 inches and 5.5 inches diagonally; the most recent iPhones measure 4 inches.

Both iPhones have an aluminum back. Despite larger screen sizes, the bodies are thinner than those of past iPhones.

To deal with concerns that a bigger phone will make using the phone with one hand difficult, Apple created the feature Reachability. Double tapping the physical button makes the picture slide down so that a user can reach over with one hand to tap something.

Video

Molly Wood, a Times technology columnist, says consumers may see a rise in the use of mobile payments now that the iPhone has a chip that will work at tap-to-pay payment terminals.Published OnSept. 9, 2014CreditCreditSoftcard, via PR Newswire

The processor inside the new iPhones is about 25 percent faster than the previous version, Phil Schiller, Apple’s head of marketing, said. The iPhones have slightly better battery life than the previous iPhone, and they include new wireless capabilities to get faster Internet speeds from cellular networks.

In addition, they support making phone calls over a Wi-Fi network and have an improved camera with a sensor that reads light and does quicker autofocus.

The starting price of an iPhone 6 with a contract is $200, while that for an iPhone 6 Plus is $300. They go on sale Sept. 19.

With the new iPhones and watch, Apple is moving deeper into the world of mobile payments. Apple demonstrated Apple Pay, a feature that allows users to pay for things in retail stores with the devices. The feature relies on near-field communication, or N.F.C., a technology that lets devices exchange information wirelessly over very short distances.

After rising initially, Apple shares ended the day down slightly.

The set of products should be the first of more to come this year. In May, Eddy Cue, Apple’s head of Internet services, said the products that the company planned to introduce this year made up the “best product pipeline that I’ve seen in my 25 years at Apple.”

A version of this article appears in print on , on Page B6 of the New York edition with the headline: Apple Goes Big With iPhone 6, and Small With a Smartwatch. Order Reprints | Today’s Paper | Subscribe